Actually, I read that Gilmour subconcsiously borrowed many elements of "Fat Old Sun" from a Kinks song called "Lazy Old Sun." I haven't heard the Kinks song but it said to have borrowed the intro and outro of it as well as some of the overall tempo.

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"You can relax on both sides of the tracks, and maniacs don't blow holes in bandsmen by remote control"
- The Gunner's Dream, Roger Waters

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"You can relax on both sides of the tracks, and maniacs don't blow holes in bandsmen by remote control"
- The Gunner's Dream, Roger Waters